The icon of marker is an image. so when i zoom in, the icon size does not change and it gets very difficult to click on the marker.
i want that i should be able to set up the marker icon so that the whole icon is georeferenced in such a way that the size of marker in terms of its dimensions on the map should be the same. for example, defining a circle with a paricular radius as marker icon as in that case the radius of circle will remain the same and marker size will appear to be changing according to zoom in or zoom out.
What you describe is the GroundOverlay. Available in osmdroid.
https://github.com/MKergall/osmbonuspack/wiki/Tutorial_5#18-using-groundoverlay